In recent years, resistance change elements that utilize changes in a resistance value to store data have been proposed (see, for example, Japanese Laid-Open Patent Publication No. 2006-120702 and Japanese Laid-Open Patent Publication No. 2006-279042). A non-volatile Resistive Random Access Memory (ReRAM) where the resistance change elements are used for a memory cell has also been developed. Generally, such resistance change elements undergo a process called forming (hereinafter, referred to as a “forming process”) after having been manufactured so that the resistance values of the resistance change elements may enter a high-resistance state or a low-resistance state. In the forming process, a voltage is applied to both electrodes until the resistance change element experiences breakdown. The breakdown allows a resistance part to be formed in the resistance change element. After the breakdown, the resistance value of the resistance part may change when a given voltage is applied to both of the electrodes of the resistance change element.
A value of a voltage for the forming process (hereinafter, referred to as a “forming voltage”) differs depending on a resistance change element and tends to have variations. Therefore, the value of the voltage to be applied to resistance change elements is set in accordance with the resistance change element that employs the highest forming voltage. However, use of a high voltage for the forming process may cause damage to the resistance change elements.